This proposal is to test the hypothesis that the abilities of human and bovine embryos to result in normal pregnancies after transfer can be assessed by measuring the luteotrophic properties and/or the concentrations of certain prostanoids in the culture media in which they were grown. Initially, the highly sensitive and repeatable dispersed bovine luteal cell system will be used to measure the luteotrophic potencies of the culture media. Culture media from 100 human embryos that resulted in pregnancy after transfer and media from 100 that did not will be studied in this system. Concentrations of PGF-2-alpha, PGE-2, PGI-2 and 5-HETE, a lipoxygenase product of arachidonic acid metabolism will be measured in the culture media and in the incubation media from the dispersed bovine luteal cells in an effort to relate differences in arachidonic acid metabolim in the embryos to their potential to result in pregnancy. Similar experiments with culture media from 200 bovine embryos cultured for 6, 12, and 24 hrs will be carried out, and attempts will be made to relate the luteotropic potencies of the culture media to embryo survivability after transfer, no further experiments will be conducted. If embryo survivability can be related to luteotropic potency as prostanoid concentration of the culture media, further experiments will be conducted in the second year to develop these findings into a repeatable, accurate and cost effective laboratory test for assessing embryo "normalcy."